Amalgam filling for teeth



May 5, 1936.

F. A. BULL. AMALGAM FILLING FOR `TEE'IH Filed Jan. lO, 1934 www Patented May 5, 1936 UNITED STATES PATENT GFFICE This invention relates to an improvement in an amalgam filling for teeth and to a process of filling cavities in teeth.

One of the objects of the invention resides in the provision of an amalgam filling which may be readily and easily built up in a tooth cavity by a dentist exercising his ordinary professional skill and which, when in place, possesses strength and durability far superior to that of the ordinary or previously known amalgam fillings and in fact having strength and durability approximating that of a gold inlay. While realizing these advantages, the present invention does not materially increase the cost of the filling nor require any more diicult operative Work.

The ordinary .amalgam filling is prepared from silver alloy filings and mercury, the same being mixed or Worked together with mortar and pestle and then tamped or pressed in the properly prepared cavity and shaped off and finished as may be appropriate in the particular case.

The present invention proposes to use the ordinary amalgam filling material such as has just been described and to combine with it a reinforcing strip or plate constituted of substantially the same silver alloy as the filings with the consequence that in the nal filling there is an amalgam bond or interlock between the plate or strip and the lling material inasmuch as the mercury which has been intermixed with the filings amalgamates with the surfaces of the silver alloy strip or plate embedded therein.

Another feature characteristic of the present invention resides in so shaping the strip or plate that it corresponds in outline to the outline of the cavity and in so disposing the strip or plate in the filling material that it is located close to the occluding surface of the tooth so that it is actually operative to take the various stresses and strains set up as an incident to mastication. Depending upon the nature of the cavity one or more reinforcing strips or plates are employed and where a plurality are employed the strips or plates are disposed in overlapping and vertically spaced relation and the marginal edges of the 4group of plates or a projection of such edges then corresponds in outline to the outline of the cavity. The present invention not only increases the strength and durability of the lling but improves it in other respects. For example, it precludes the amalgam lling material from spheroiding off of the corners of the bottom of the cavity, the plate, when tamped into position, exerting downward pressure on all portions of the amalgam filling simultaneously and thereby positively pressing the filling material into all portions of the cavity. Then again it prevents displacement of the .amalgam lling material during the setting period.

Other objects and advantages reside in certain novel features of the construction, arrangement and combination of parts which will be hereinafter more fully described and particularly pointed out in the appended claims, reference being had to be accompanying drawing, forming a part of this specification, and in which:

Figure 1 is a perspective view showing a tooth having one type of cavity and illustrating how the reinforcing plate is related to the filling material although the portion of the lling material which, `5 in the nished job, covers the exposed surfaces of the plate, has been omitted for the sake of illustration Figure 2 is a view partly in side elevation and partly in transverse vertical section showing the tooth of Figure 1 with the filling complete;

Figure 3 is a perspective view of the reinforcing plate used in the filling of Figures 1 and 2;

Figure 4 is a plan view of the tooth shown in Figures l and 2 with a portion of the amalgam 25 filling material omitted and illustrating diagrammatically the clamp employed to shape the peripheral surfaces of the filling material during the filling operation;

Figure 5 is a view partly in elevation and partly 30 in transverse vertical section showing the filling adapted for another type of cavity;

Figure 6 is a plan View of the tooth and filling shown in Figure 5, with a portion of the amalgam filling material omitted for the sake of 'illustra- 35 tion; and

Figures '7, 8 and 9 are views partly in side elevation and partly in transverse vertical section, illustrating the invention adapted to three other different types of cavities. 40

Referring to the drawing, and more particularly to Figures 1 to 4, inclusive, a tooth T is shown as having a cavity C prepared therein, the cavity C being illustrated as of the type which is extensive on one side of the tooth andrwhich is of reduced extent horizontally toward the center of the tooth. In filling such a cavity in the manner proposed by the present invention, a reinforcing plate I is first provided, this reinforcing plate being cut to an outline corresponding to the outline of the cavity and consequently having a body portion 2 here shown as approximately semi-circular in shape and a reduced extension 3. This plate l is constituted of the same or substantially the same silver alloy as the lings which are mixed up with the mercury to provide the amalgam filling material 5 or, in other words, it is of such silver alloy composition that it will amalgamate permanently with the amalgam filling material 5. In filling the tooth theY amalgam filling material 5 prepared in the usual way is tamped into the previously prepared cavity and then the plate I is put on top 0f Ysuch material and pressed and Worked thereinto until it occupies the position shown in Figure 2, that is close to the occluding surface of the tooth although covered by a layer 5' of the filling material. During this operation the usual clamp 6 shown diagrammatically in Figure 4 is placed in position around the tooth in accordance with standard dentalY practice.

In Figures 5 and 6 a tooth 'I" is shown as having a cavity o-f the type which has enlarged ends 'I and 8 at the sides of the tooth and a narrow connecting neck across the center of the tooth. Such acavity is filled in the same manner as that just described except that thereinforcing plate I@ is shaped to correspond to the outline of the cavity,

that is to say, it has enlarged en-ds I I and a narrow connecting neck I2.

In Figure '7 the Vtooth T2 has a cavity of the type shown at I3 and in this form it is clear how the reinforcing plate I4, by pressing downwardly on allportions of the filling, prevents spheroiding of the amalgam filling material I5 out of the portions II'and II'of the cavity.

If the cavity is extensive as illustrated in the toothT3 ofFigureS or the tooth T4 of Figure 9, a pluralityof-reinforcing plates may be provided. As illustrated in Figure 8, plates I8 and I9 may be incorporated in the amalgam filling material 26 With the-plate I8 disposed slightly below the plate I9V and'underlying the same to some extent. By so combining a plurality of plates in the amalgam filling it is `possible to properly reinforce the entire occluding surface of the tooth even though some portions of such surface are disposed well Y above other portions thereof.

The manner of combining the reinforcing plates 2I and 22 with the cavity of the tooth T4 shown in Figure 9 is especially advantageous Where the cavity or portion thereof is unusually deep.

In all forms of the invention the reinforcing plate or strip, due to its correspondence in composition to the filings of the amalgam filling material is permanently amalgamated with the amalgam filling material in the finished job and hence-Y is permanently and securely interlocked therewith. Creeping of the filling material along the reinforcing element is precluded. Not only is tensile strength of the filling improved but its capacity to resist shear and to withstand the strains set up by compressive forces is substantially improved. Moreover, the reinforcing element is so related to the occluding surface of the tooth that it takes care of the forces set up by masticati-on. While these advantages are realized, the operative Work required of the dentist is not increased or rendered more difficult. Only the ordinary dental skill is required. The'cost of the filling is not increased in any material manner and yet substantially all of the advantages of a gold inlay are had.

If desired, the reinforcing elements may be serrated to enhance the interlock between them and the amalgam filling material.

While I have shown and described a number of Ways in which the invention may be carried out, it is to be understood that the particular examples shown are merely for the purpose of illustration and that various changes in the size, shape and arrang-ementvof the partsmay be had, as will be obvious to those skilled in the art, without departing from the spirit of the invention or the scope of the subjoined claims.

The invention claimed is:

1. A reinforced amalgam filling for teeth comprising the usual amalgam filling material made up of silver alloy filings and mercury and a reinforcing element of substantially plate-like form f and of substantially the same compositi-on as said silver alloy filings of the amalgam filling material embedded in said amalgam filling material and vunited thereto by amalgamation of its sur face portions with said filling material. Y

2. A reinforced amalgam filling for teeth comprising the usual amalgam filling material made up of silver alloy filings and mercury and a reinforcing element of substantially plate-like form and `of substantially the same composition as said silver alloy filings of the amalgamv filling material and embedded in said amalgam filling material and united thereto by amalgamation of its surface portions with said filling material, said reinforcing element being disposed adjacent to and substantially co-extensive with the occluding surface of the tooth whereby to substantially increase the tensile strength of the filling and also enhance its capacity to resist crushing forces.

3. A reinforced amalgam filling for teeth comprising the usual amalgam filling material made of silver alloy fillings and mercury and a reinforcing element of substantially plateelike form and of substantially the same composition as said silver alloy filings of the amalgam filling material and embedded in said amalgam filling material and united thereto by amalgamation of its surface porti-ons with said filling material, said reinforcing element corresponding in outline to the outline of an-d being substantially co-extensive with the cavity.

4. A reinforced amalgam filling for teeth comprising the usual amalgam filling material made of silver alloy filings and mercury and a reinforcing element of :substantially plate-like form and l FRANCIS' A. BULL. 

